dual-glo luciferase assay system - please select your country

Revised 9/15 TM058

T E C H N I C A L M A N U A L

Dual-Glo® Luciferase Assay SystemInstructions for use of Products E2920, E2940 and E2980.

Promega Corporati on · 2800 Woods Hollow Road · Madison, WI 53711-5399 USA · Toll Free in USA 800-356-9526 · 608-274-4330 · Fax 608-277-2516 1www.promega.com TM058 · Revised 9/15

1. Description .........................................................................................................................................2

2. Product Components and Storage Conditions ........................................................................................2

3. Performing the Dual-Glo® Luciferase Assay ...........................................................................................53.A. General Considerations ...............................................................................................................53.B. Reagent Preparation ...................................................................................................................63.C. Assay Procedure .........................................................................................................................7

4. Related Products .................................................................................................................................8

5. References ........................................................................................................................................ 11

6. Appendix .......................................................................................................................................... 116.A. Overview of the Dual-Glo® Luciferase Assay System .................................................................... 116.B. Development of the Assay .......................................................................................................... 12 Quenching Eff ect ...................................................................................................................... 146.C. Data Analysis ........................................................................................................................... 16 Background Subtraction ............................................................................................................ 16 Normalizing Ratios ................................................................................................................... 16 Relative Response Ratios........................................................................................................... 176.D. Conditions Aff ecting Assay Performance ..................................................................................... 18 Culture Medium ....................................................................................................................... 20 Serum ...................................................................................................................................... 21 Phenol Red .............................................................................................................................. 22 Organic Solvents ...................................................................................................................... 23 Temperature ............................................................................................................................ 246.E. Summary of Changes................................................................................................................. 25

All technical literature is available at: www.promega.com/protocols/ Visit the web site to verify that you are using the most current version of this Technical Manual.

E-mail Promega Technical Services if you have questions on use of this system: [email protected]

Dual-Glo® Luciferase Assay System

2 Promega Corporati on · 2800 Woods Hollow Road · Madison, WI 53711-5399 USA · Toll Free in USA 800-356-9526 · 608-274-4330 · Fax 608-277-2516TM058 · Revised 9/15 www.promega.com

1. Description

In cell biology research and pharmaceutical discovery, it is common to test a wide variety of experimental conditions or a large number of chemical compounds for their eff ects on cellular physiology (1,2). Traditionally, the ease and sensitivity of fi refl y luciferase assays have made it relatively simple to monitor the upregulation of genetic elements. However, it has been more diffi cult to measure downregulation of genes because of the diffi culty in discriminating between cell death and cellular downregulation. Normalizing the expression of an experimental reporter to the expression of a control reporter can help diff erentiate between specifi c and nonspecifi c cellular responses. This normalization can also control for transfection effi ciencies.

Firefl y and Renilla luciferases are widely used as co-reporters for these normalized studies because both assays are quick, easy and sensitive. Firefl y luciferase is a 61kDa and Renilla luciferase a 36kDa protein (3–5). Both are monomeric and neither requires post-translational processing, so they can function as genetic reporters immediately upon translation.

The Dual-Glo® Luciferase Assay System(a–c) is designed to allow high-throughput analysis of mammalian cells containing genes for fi refl y and Renilla luciferases grown in 96- or 384-well plates (Figure 1). The Dual-Glo® Luciferase Reagent can be added directly to cells in growth medium without washing or preconditioning. This reagent induces cell lysis and acts as a substrate for fi refl y luciferase, which has a half-life of approximately 2 hours. Addition of the Dual-Glo® Stop & Glo® Reagent quenches the luminescence from the fi refl y reaction by at least 10,000-fold and provides the substrate for Renilla luciferase in a reaction that can also be read within 2 hours (with a similar retention in signal). The Dual-Glo® Luciferase Assay System is designed to work in growth media commonly used for mammalian cells with or without added serum. For an overview and information on the development of the Dual-Glo® Luciferase Assay System, see Sections 6.A and B.

To see articles that cite the use of the Dual-Glo® Luciferase Assay System, visit: www.promega.com/resources/tools/citations/

2. Product Components and Storage Conditions

P R O D U C T S I Z E C AT. #

Dual-Glo® Luciferase Assay System 10ml E2920

Each system contains suffi cient components to prepare 10ml of each reagent. Includes:

• 10ml Dual-Glo® Luciferase Buff er• 1 vial Dual-Glo® Luciferase Substrate (lyophilized)• 10ml Dual-Glo® Stop & Glo® Buff er• 100µl Dual-Glo® Stop & Glo® Substrate



Dual-Glo® Luciferase Assay System 100ml E2940

Each system contains suffi cient components to prepare 100ml of each reagent. Includes:

• 100ml Dual-Glo® Luciferase Buff er• 1 vial Dual-Glo® Luciferase Substrate (lyophilized)• 100ml Dual-Glo® Stop & Glo® Buff er• 1,000µl Dual-Glo® Stop & Glo® Substrate


Dual-Glo® Luciferase Assay System 10 × 100ml E2980

Each system contains suffi cient components to prepare 1,000ml of each reagent. Includes:

• 10 × 100ml Dual-Glo® Luciferase Buffer• 10 vials Dual-Glo® Luciferase Substrate (lyophilized)• 10 × 100ml Dual-Glo® Stop & Glo® Buffer• 10 × 1,000µl Dual-Glo® Stop & Glo® Substrate

Storage Conditions: Store the Dual-Glo® Stop & Glo® Substrate and the lyophilized Dual-Glo® Luciferase Substrate at –20°C. The substrates also may be stored at 4°C for up to two weeks. Store the Dual-Glo® Stop & Glo® Buff er and the Dual-Glo® Luciferase Buff er below 25°C. Buff er storage at room temperature is recommended to prevent the need for temperature equilibration when the reagents are reconstituted. Use the reconstituted Dual-Glo® Luciferase Reagent on the day it is prepared or store at –70°C after preparation for up to six months. Prepare the Dual-Glo® Stop & Glo® Reagent on the day it is to be used.

Caution: The lyophilized Dual-Glo® Luciferase Substrate contains dithiothreitol (DTT) and is therefore classified as hazardous. The reconstituted reagent is not known to present a hazard, as the concentration of DTT is less than 1%. However, we recommend the use of gloves, lab coats and eye protection when working with these and all chemical reagents. In addition, the Dual-Glo® Stop & Glo® Substrate contains a highly volatile solvent. Please pipet carefully and close the cap tightly after use.

Note: If Dual-Glo® Stop & Glo® Buff er precipitates upon freezing, it can be resolubilized without aff ecting solution performance. To resolubilize precipitate, store the Dual-Glo® Stop & Glo® Buff er at room temperature for 3 days or at 4°C for 2 weeks before use. Precipitate can also be resolubilized by heating to 37°C for up to 2 hours with vigorous shaking. Dual-Glo® Stop & Glo® Buff er should be equilibrated to room temperature for use.

!


98

91

MA

Add Dual-Glo® Luciferase Assay Reagent to the plate.

Incubate at 20–25°C for 10 minutes–2 hours.

Incubate at 20–25°C for10 minutes–2 hours.

Measure firefly luminescence.

Add Dual-Glo® Stop & Glo® Reagent to the plate.

Measure Renilla luminescence.

Calculate ratio of firefly:Renilla luminescence for each well. Normalize the sample well ratioto the ratio from a control(or series of control) well(s).

Figure 1. Dual-Glo® Luciferase Assay protocol. Firefl y luciferase is produced, measured and quenched, followed by Renilla luciferase, in the same well.


3. Performing the Dual-Glo® Luciferase Assay

3.A. General Considerations

The Dual-Glo® Luciferase Assay System is designed for use in mammalian cell culture medium and is optimized for use with the following types of media containing 0–10% serum: RPMI 1640, DMEM, MEM, and F12. The reagents have been developed so that the signals for fi refl y and Renilla luciferases are relatively stable and have a half-life of approximately 2 hours. Media/sera combinations aff ect the stability of each luminescent signal, so experimental determination of assay performance is recommended for media/sera combinations not listed above (see Section 6.D). The luminescence signal of each reporter also can be aff ected by the presence of phenol red, organic solvents or changes in temperature (Section 6.D).

Because the luminescent signals are aff ected by assay conditions, raw results should be compared only between samples measured at the same time and using the same medium/serum combination. Incorporation of consistent control wells on each plate provides the ability to calculate a normalized fi refl y luminescence/Renilla luminescence ratio for each sample well. These normalized ratios will remain essentially constant (±10%) for samples in a plate measured during the recommended 2-hour measurement window. Incorporating positive and negative control wells within a plate or experiment provides the ability to calculate a Relative Response Ratio (RRR). The RRR can be used to compare results between experiments that do not use the same media/sera combination or have been aff ected by changes in temperature or other variables (see Section 6.C).

Because a small amount of time is required for complete cell lysis and enzyme equilibration, the reagents of the Dual-Glo® Luciferase Assay System should be added to plates 10 minutes before quantifying luminescence. For maximal light intensity, samples should be measured within 2 hours of reagent addition. The Dual-Glo® Luciferase Reagents are not designed for use with the automated injectors that are integrated into some luminometers, as excessive reagent foaming may occur.

To achieve linear assay performance at low light levels, the background luminescence must be subtracted from all readings. Some luminometers also require verifi cation of linear response at high light levels (consult your luminometer instrument manual for usage information).


3.B. Reagent Preparation

1. Transfer the contents of one bottle of Dual-Glo® Luciferase Buff er to one bottle of Dual-Glo® Luciferase Substrate to create the Dual-Glo® Luciferase Reagent. Mix by inversion until the substrate is thoroughly dissolved.

2. Calculate the amount of Dual-Glo® Stop & Glo® Reagent needed to perform the desired experiments. Dilute the Dual-Glo® Stop & Glo® Substrate 1:100 into an appropriate volume of Dual-Glo® Stop & Glo® Buff er in a new container.

Example: If 6ml of Dual-Glo® Stop & Glo® Reagent is needed, dilute 60µl of Dual-Glo® Stop & Glo® Substrate into 6ml of Dual-Glo® Stop & Glo® Buff er. For Cat.# E2940 and E2980, if the entire bottle of Dual-Glo® Stop & Glo® Buff er is to be used at one time, transfer the entire contents of the Dual-Glo® Stop & Glo® Substrate into the buff er. For Cat.# E2920, combine 10ml of Dual-Glo® Stop & Glo® Buff er and 100µl of Dual-Glo® Stop & Glo® Substrate.

Notes:

1. Assay reagents are stable at room temperature for several hours (see Notes 2 and 3). Freezing the reagent can reduce the loss of activity of the Dual-Glo® Luciferase Reagent. Do not thaw the reconstituted reagent at temperatures above 25°C. Mix well after thawing. The most convenient and eff ective method for thawing is to place the reagent in a room temperature water bath. Prepare only the amount of Dual-Glo® Stop & Glo® Reagent required. For best results, prepare the Dual-Glo® Stop & Glo® Reagent immediately before use.

2. Dual-Glo® Luciferase Reagent Stability: Liquid reagent has approximately a 10% loss of fi refl y RLU after 8 hours at room temperature and after 48 hours at 4°C. Frozen reagent has approximately a 10% loss of fi refl y RLU after 1 week at –20°C and after 6 months at –70°C. Do not store the reagent at –20°C for longer than 1 week. The reagent can be exposed to 5 freeze-thaw cycles with approximately a 15% loss in fi refl y RLU. Holding or storing the reconstituted reagent may cause Renilla RLU to rise.

3. Approximate stability of Dual-Glo® Stop & Glo® Reagent after reconstitution: 8.1% loss after 8 hours at room temperature, 8.5% loss after 24 hours at 4°C. We recommend that the Dual-Glo® Stop & Glo® Reagent always be prepared immediately before use.

4. Light intensity is a measure of the rate of catalysis by the luciferases and is therefore temperature sensitive. The temperature optimum for the activity of both luciferases is approximately room temperature (20–25°C), so it is important that the reagents be equilibrated to room temperature before beginning measurements. To avoid the need to temperature equilibrate reagents before use, store the Dual-Glo® Luciferase Buff er and the Dual-Glo® Stop & Glo® Buff er at room temperature. If reagents are colder than room temperature, place them in a room temperature water bath to equilibrate before use.

5. To achieve maximum reproducibility, equilibrate cells in media to room temperature before performing luciferase measurements.


3.C. Assay Procedure

1. Remove multiwell plates containing mammalian cells from the incubator. Make certain that the plates are compatible with the type of luminometer being used.

2. Measuring fi refl y luciferase activity: Add a volume of Dual-Glo® Luciferase Reagent equal to the culture medium volume to each well and mix. For 96-well plates, typically 75µl of reagent is added to cells grown in 75µl of medium. For 384-well plates, typically 20µl of reagent is added to cells grown in 20µl of medium.

3. Wait at least 10 minutes, then measure the fi refl y luminescence (consult your luminometer manual for proper use of the instrument). Optimal results will be generated if the luminescence is measured within 2 hours of addition of Dual-Glo® Luciferase Reagent.

4. Measuring Renilla luciferase activity: Add a volume of Dual-Glo® Stop & Glo® Reagent equal to the original culture medium volume to each well and mix. As noted in Step 2, this volume is typically 75µl for 96-well plates and 20µl for 384-well plates.

Note: Dual-Glo® Stop & Glo® Reagent should be added to plate wells within 4 hours of addition of Dual-Glo® Luciferase Reagent.

5. Wait at least 10 minutes, then measure luminescence. Renilla luminescence should be measured in the same plate order as the fi refl y luminescence was measured (Step 3). Optimal results will be generated if the luminescence is measured within 2 hours of addition of Dual-Glo® Stop & Glo® Reagent.

6. Calculate the ratio of luminescence from the experimental reporter to luminescence from the control reporter. Normalize this ratio to the ratio of a control well or series of control wells that are treated consistently on all plates (see Section 6.C). This normalization provides optimal and consistent results from the Dual-Glo® Luciferase Assay System. Relative Response Ratios can then be calculated from the Normalized Ratios. See Section 6.C for more information and sample calculations.


4. Related Products

pGL4 Luciferase Reporter VectorsPlease visit www.promega.com to see a complete listing of our reporter vectors.

Vector

Multiple Cloning Region

Reporter Gene

Protein Degradation

Sequence

Reporter Gene

Promoter

Mammalian Selectable

Marker Cat.#

pGL4.10[luc2] Yes luc2A No No No E6651

pGL4.11[luc2P] Yes “ hPEST No No E6661

pGL4.12[luc2CP] Yes “ hCL1-hPEST No No E6671

pGL4.13[luc2/SV40] No “ No SV40 No E6681

pGL4.14[luc2/Hygro] Yes “ No No Hygro E6691

pGL4.15[luc2P/Hygro] Yes “ hPEST No Hygro E6701

pGL4.16[luc2CP/Hygro] Yes “ hCL1-hPEST No Hygro E6711

pGL4.17[luc2/Neo] Yes “ No No Neo E6721

pGL4.18[luc2P/Neo] Yes “ hPEST No Neo E6731

pGL4.19[luc2CP/Neo] Yes “ hCL1-hPEST No Neo E6741

pGL4.20[luc2/Puro] Yes “ No No Puro E6751

pGL4.21[luc2P/Puro] Yes “ hPEST No Puro E6761

pGL4.22[luc2CP/Puro] Yes “ hCL1-hPEST No Puro E6771

pGL4.23[luc2/minP] Yes “ No minP No E8411

pGL4.24[luc2P/minP] Yes “ hPEST “ No E8421

pGL4.25[luc2CP/minP] Yes “ hCL1-PEST “ No E8431

pGL4.26[luc2/minP/Hygro] Yes “ No “ Hygro E8441

pGL4.27[luc2P/minP/Hygro] Yes “ hPEST “ Hygro E8451

pGL4.28[luc2CP/minP/Hygro] Yes “ hCL1-PEST “ Hygro E8461

pGL4.29[luc2P/CRE/Hygro] No “ hPEST CRE Hygro E8471

pGL4.30[luc2P/NFAT-RE/Hygro] No “ hPEST NFAT-RE Hygro E8481

pGL4.31[luc2P/GAL4UAS/Hygro] No “ hPEST GAL4UAS Hygro C9351

pGL4.32[luc2P/NF-B-RE/Hygro] No “ hPEST NF-B-RE Hygro E8491

pGL4.33[luc2P/SRE/Hygro] No “ hPEST SRE Hygro E1340

pGL4.34[luc2P/SRF-RE/Hygro] No “ hPEST SRF-RE Hygro E1350

pGL4.36[luc2P/MMTV/Hygro] No “ hPEST MMTV Hygro E1360

pGL4.50[luc2/CMV/Hygro] No “ No CMV Hygro E1310

pGL4.51[luc2/CMV/Neo] No “ No CMV Neo E1320Aluc2 = synthetic fi refl y luciferase gene. BhRluc = synthetic Renilla luciferase gene.


pGL4 Luciferase Reporter Vectors (continued)

Vector

Multiple Cloning Region

Reporter Gene

Protein Degradation

Sequence

Reporter Gene

Promoter

Mammalian Selectable

Marker Cat.#

pGL4.70[hRluc] Yes hRlucB No No No E6881

pGL4.71[hRlucP] Yes “ hPEST No No E6891

pGL4.72[hRlucCP] Yes “ hCL1-hPEST No No E6901

pGL4.73[hRluc/SV40] No “ No SV40 No E6911

pGL4.74[hRluc/TK] No “ No HSV-TK No E6921

pGL4.75[hRluc/CMV] No “ No CMV No E6931

pGL4.76[hRluc/Hygro] Yes “ No No Hygro E6941

pGL4.77[hRlucP/Hygro] Yes “ hPEST No Hygro E6951

pGL4.78[hRlucCP/Hygro] Yes “ hCL1-hPEST No Hygro E6961

pGL4.79[hRluc/Neo] Yes “ No No Neo E6971

pGL4.80[hRlucP/Neo] Yes “ hPEST No Neo E6981

pGL4.81[hRlucCP/Neo] Yes “ hCL1-hPEST No Neo E6991

pGL4.82[hRluc/Puro] Yes “ No No Puro E7501

pGL4.83[hRlucP/Puro] Yes “ hPEST No Puro E7511

pGL4.84[hRlucCP/Puro] Yes “ hCL1-hPEST No Puro E7521Aluc2 = synthetic fi refl y luciferase gene. BhRluc = synthetic Renilla luciferase gene.

Luciferase Assay Systems

Product Size Cat.#Steady-Glo® Luciferase Assay System* 100ml E2520

Bright-Glo™ Luciferase Assay System* 100ml E2620

Dual-Luciferase® Reporter Assay System* 100 assays E1910

Luciferase Assay System* 100 assays E1500

Luciferase Assay Reagent 1,000 assays E1483

Renilla Luciferase Assay System* 100 assays E2810

QuantiLum® Recombinant Luciferase* 1mg E1701

EnduRen™ Live Cell Substrate* 0.34mg E6481

ViviRen™ Live Cell Substrate* 0.37mg E6491

*Additional Sizes Available.


4. Related Products (continued)

Transfection Reagent

Product Size Cat.#FuGENE® HD Transfection Reagent 1ml E2311

5 × 1ml E2312

Luminometers

Product Size Cat.#GloMax®-Multi+ Detection System with Instinct™ Software: Base Instrument with Shaking each E8032

GloMax®-Multi+ Detection System with Instinct™ Software: Base Instrument with Heating and Shaking each E9032

GloMax® 20/20 Luminometry System each E5311

GloMax® 20/20 Luminometry System with Single Auto-Injector each E5321

GloMax® 20/20 Luminometry System with Dual Auto-Injector each E5331

GloMax® 96 Microplate Luminometer each E6501

GloMax® 96 Microplate Luminometer with Single Injector each E6511

GloMax® 96 Microplate Luminometer with Dual Injector each E6521

Plasmid DNA Purifi cation System

Product Size Cat.#PureYield™ Plasmid Midiprep System 25 preps A2492

100 preps A2495

300 preps A2496

PureYield™ Plasmid Maxiprep System 10 preps A2392

25 preps A2393


5. References

1. Alam, J. and Cook, J.L. (1990) Reporter genes: Application to the study of mammalian gene transcription. Anal. Biochem. 188, 245–54.

2. Wood, K.V. (1991) In: Bioluminescence and Chemiluminescence: Current Status, Stanley, P., and Kricka, L., eds., John Wiley and Sons, Chichester, NY, 543.

3. Wood, K.V. et al. (1984) Synthesis of active fi refl y luciferase by in vitro translation of RNA obtained from adult lanterns. Biochem. Biophys. Res. Comm. 124, 592–6.

4. deWet, J.R. et al. (1985) Cloning of fi refl y luciferase cDNA and the expression of active luciferase in Escherichia coli. Proc. Natl. Acad. Sci.USA 82, 7870–3.

5. Matthews. J.C. et al. (1977) Purifi cation and properties of Renilla reniformis luciferase. Biochemistry 16, 85–91.

6. Appendix

6.A. Overview of the Dual-Glo® Luciferase Assay System

Transcriptional regulation coupled to reporter gene expression is routinely used to study a wide range of physiological responses. A common example is the analysis of receptor function by quantitating the action of specifi c reporter response elements on gene expression. Firefl y luciferase has been used as a simple, convenient and sensitive reporter gene for this type of analysis.

An increase in the transcription or translation of a reporter molecule, like fi refl y luciferase, is easily tracked in a biological system. Firefl y luciferase is immediately functional upon translation. Thus if the amount of luminescence from an experimental sample is greater than the luminescence from a control sample, an increase in transcription or translation has occurred.

Studies of antagonists or other factors that decrease transcription or translation are diffi cult to interpret when using a single reporter gene. A decrease in an experimental reporter response (fi refl y luciferase in this case) can be caused by a specifi c eff ect on the reporter or by a global eff ect such as cell death. Normalization of an experimental reporter with a control reporter from the same sample, such as Renilla luciferase, allows a distinction to be made between specifi c and global eff ects. A decrease in fi refl y luminescence with Renilla luminescence remaining unchanged indicates a specifi c impact of the experimental condition. A decrease of both luminescences indicates a global impact on the cell or cell population (i.e., cell death, inhibition of cell growth, variable initial cell numbers).


6.A. Overview of the Dual-Glo® Luciferase Assay System (continued)

The Dual-Luciferase® Reporter Assay System (DLR™ Assay System, Cat.# E1910) allows measurement of both fi refl y and Renilla luciferases from a single sample. This assay system, however, generates luminescence that rapidly decreases in intensity. The fi refl y luciferase signal decreases 50% in approximately 12–15 minutes, and the Renilla luciferase signal decreases 50% in less than 3 minutes. These signal kinetics make the measurement of fi refl y and Renilla luciferases diffi cult if large numbers of samples are to be measured in 96- or 384-well plates. Although robotic systems can easily add reagents to all the samples on a plate at the same time, the signals are too unstable to easily measure the luminescence from the entire plate without having to calculate time corrections.

The Dual-Glo® Luciferase Assay System, with its stabilized luminescent signals and half-life of approximately 2 hours, easily can be used to measure both fi refl y and Renilla luminescence in multiwell plates. Many plates containing experimental samples can be batch processed; all plates can be fi lled with reagent at one time, and the luminescence from each plate can be measured in series. In this way, the Dual-Glo® Luciferase Assay System can easily and rapidly quantitate both fi refl y and Renilla luciferases, allowing one to distinguish between global and specifi c eff ects.

6.B. Development of the Assay

Firefl y and Renilla luciferases have distinct evolutionary origins and have very diff erent enzyme structures and substrates. Promega has been able to exploit these diff erences so that the two luciferases can be measured in succession, with fi refl y luciferase luminescence elicited by one reagent, while a second reagent simultaneously quenches the fi refl y luciferase and elicits Renilla luciferase luminescence.

Firefl y and Renilla luciferases do not require post-translational modifi cation and thus are fully functional enzymes immediately after translation (3,4). In order to generate luminescence fi refl y luciferase requires beetle luciferin, ATP, magnesium and molecular oxygen. Renilla luciferase requires only coelenterate luciferin (coelenterazine) and molecular oxygen (Figure 2). Firefl y and Renilla luciferases undergo spontaneous inactivation after generating luminescence. This inactivation causes the “fl ash”-type kinetics seen in assays that have been optimized for maximal assay sensitivity, like the DLR™ Assay System (Figure 3). In order to generate luminescence with signal stability that is amenable to robotic measurements, the rate of inactivation and subsequently the rate of catalysis must be slowed. For this reason, “glo”-type reagents developed for use in high-throughput screening, like the Steady-Glo® and Dual-Glo® Reagents, have lower luminescences than “fl ash”-type reagents that have been developed for maximal sensitivity, like the Luciferase and DLR™ Assay Reagents.


1399MA03_6A

HO S

N S

NO S

N S

NOCOOH

+ATP+O2

Recombinant FireflyLuciferase

+AMP+PPi+CO2+Light

Beetle Luciferin Oxyluciferin

Mg2+

NH

N N

O OH

+O2

HO

N

N NH

OOH

+CO2+Light

HO

RenillaLuciferase

Coelenterazine Coelenteramide

Figure 2. Bioluminescent reactions catalyzed by fi refl y and Renilla luciferases. Mono-oxygenation of beetle luciferin is catalyzed by fi refl y luciferase in the presence of Mg2+, ATP and molecular oxygen. Unlike beetle luciferin, coelenterazine undergoes mono-oxygenation catalyzed by Renilla luciferase but requires only molecular oxygen.

Fire

fly L

umin

esce

nce

(RLU

)

Time (Minutes)

100 20 40 60 80 100 120

100

1,000

10,000

Reni

lla L

umin

esce

nce

(RLU

)

Time (Minutes)

100 20 40 60 80 100 120

100

1,000

10,000

3619MA02_2A

A. B.DLR™Dual-Glo™

Figure 3. Comparison of the signal decay of luciferases in Dual-Glo® Reagent and DLR™ Assay Reagent. The two luciferase assay reagents were compared using 1.67 × 10–9M (plus 1mg/ml gelatin) firefly and Renilla luciferase (20µl and 100µl of enzyme mix were used with DLR™ and Dual-Glo® Reagents, respectively). The luciferases were diluted in RPMI 1640 before assaying with Dual-Glo® Luciferase Reagent and in Passive Lysis Buffer (Cat.# E1941) before assaying with DLR™ Assay Reagent. The DLR™ Assay measurements were taken immediately after reagent addition, while the Dual-Glo® measurements were taken after a 10-minute incubation at room temperature. Luminescence was integrated over 0.5 seconds per well at regular intervals until 2 hours after reagent addition. Panel A. Firefly luciferase activity in Dual-Glo® and DLR™ Assays. Panel B. Renilla luciferase activity in Dual-Glo® and DLR™ Assays.


6.B. Development of the Assay (continued)

Quenching Eff ect

Providing the ability to measure fi refl y luminescence is only one of the requirements for the Dual-Glo® Luciferase Assay System. After measurement of the fi refl y luminescence, the Dual-Glo® Stop & Glo® Reagent must simultaneously quench fi refl y luminescence and generate Renilla luminescence.

The Dual-Glo® Stop & Glo® Reagent has been designed to decrease the luminescence of the fi refl y luciferase reaction by at least 10,000-fold (Figure 4). Thus if the fi refl y luciferase luminescence generated 530,000 Relative Light Units per second, the maximum fi refl y luminescence measured 10 minutes after the Dual-Glo® Stop & Glo® Reagent addition would be 53 Relative Light Units per second. The promoter for the control reporter (either fi refl y or Renilla luciferase) should be chosen so that the luminescence from the fi refl y luciferase is no more than 100 times the luminescence from the Renilla luciferase. If this is the case, the fi refl y luciferase luminescence will contribute no more than 1% to the Renilla luciferase luminescence, and variability in the fi refl y luciferase signal will not noticeably aff ect the Renilla luciferase signal.

3620MA02_2AFirefly

LuciferaseActivity

QuenchedLuminescence

RenillaLuciferase

Activity

Lum

ines

cenc

e (R

LU)

10

100

1,000

10,000

100,000

1,000,000

10,000,0001,900,000

30

(60,000-foldquench)

170,000

Figure 4. Measurement of luciferase activities before and after addition of Dual-Glo® Stop & Glo® Reagent. Both fi refl y and Renilla luciferase reporter activities were quantitated using a 100µl sample of purifi ed fi refl y or Renilla luciferase (1.67 × 10–9M and 1.67 × 10–10M, respectively, with 1mg/ml gelatin). The concentration of Renilla luciferase is 10-fold less than that of fi refl y luciferase. To demonstrate the effi cient quenching of fi refl y luciferase by Dual-Glo® Stop & Glo® Reagent, an equal volume of Dual-Glo® Stop & Glo® Buff er (which does not contain the substrate for Renilla luciferase) was added to the Dual-Glo® Luciferase Reagent with fi refl y luciferase. Firefl y luciferase luminescence was quenched by greater than 4 orders of magnitude with 0.0016% residual activity. RLU = relative light units.

The Dual-Glo® Stop & Glo® Reagent has been designed to provide simultaneous quenching of the fi refl y luciferase signal and sustained luminescence for the Renilla luciferase reaction. Renilla luciferase does not use any of the substrates for the fi refl y reaction except molecular oxygen. This permits the Dual-Glo® Stop & Glo® Reagent to both quench the fi refl y reaction and generate the Renilla luciferase reaction. Renilla luciferase is similar to fi refl y luciferase in that the enzyme inactivates itself. As with the fi refl y luciferase, the rate of catalysis must be slowed if the luminescent signal is to be stabilized. “Glo”-type Renilla assays (Dual-Glo® Luciferase Assay) are therefore not as sensitive as “fl ash”-type assays (DLR™ and Renilla Luciferase Assays).


Unlike the fi refl y luciferase substrate (beetle luciferin), coelenterazine will auto-oxidize in the absence of Renilla luciferase. This enzyme-independent reaction is termed autoluminescence. Reaction conditions such as high detergent levels created in homogeneous assays can increase the level of autoluminescence, which can limit the sensitivity of the Renilla luciferase reporter system. The Dual-Glo® Luciferase Assay System uses unique technology that reduces autoluminescence to levels that are often undetectable, thereby increasing the sensitivity of the Renilla luciferase reagent of the Dual-Glo® Luciferase Assay System by >100-fold over nonoptimized reagents (Figure 5).

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Figure 5. The Dual-Glo® Luciferase Assay System is optimized for minimal autoluminescence from Renilla luciferase substrate. Luminescence from a titration of Renilla luciferase was compared in Dual-Glo® Reagent before and after optimization for homogeneous assay formats. Luciferase concentrations varied over a titration range of 1 × 10–12 to 1 × 10–19 moles/reaction. One hundred microliters of Renilla luciferase in RPMI 1640 (containing 1mg/ml gelatin) was added to 100µl of Dual-Glo® Luciferase Reagent and 100µl of Dual-Glo® Stop & Glo® Reagent, either optimized or nonoptimized for homogeneous assay format. Samples were incubated for 10 minutes at 22°C, then measured on a Turner Designs Model 20e luminometer. Light emission was integrated over 5 seconds after an initial 2-second preread delay. Limit of detection values shown (horizontal lines labeled Optimized and Nonoptimized) represent background plus three standard deviations and were determined for each assay by performing the assay without enzyme.


6.C. Data Analysis

Background Subtraction

For maximal accuracy, the luminescence measurements of both fi refl y and Renilla luciferases should be background-subtracted. Neither enzyme is endogenously expressed in mammalian cells, so the source of background luminescence is either a characteristic of the luminometer or of the luminescent substrate. Beetle luciferin, one of the fi refl y luciferase substrates, does not generate light in the absence of luciferase in the Dual-Glo® Reagents. A proprietary chemistry minimizes the enzyme-independent luminescence (autoluminescence) exhibited by coelenterate luciferin, the substrate for Renilla luciferase in the Dual-Glo® Stop & Glo® Reagent. Background luminescence for both luciferase reagents therefore may not be measurable above the background on many luminometers.

Background measurements for fi refl y luciferase should be taken from samples consisting of nontransfected cells and Dual-Glo® Luciferase Reagent. For Renilla luciferase, background measurements should be taken from samples containing nontransfected cells and both Dual-Glo® Luciferase Reagent and Dual-Glo® Stop & Glo® Reagent. Sample volumes for background measurements must be the same as experimental sample volumes and contain the same media/sera combinations as the experimental samples.

Normalizing Ratios

Normalizing the results from each experimental sample to control samples repeated on each plate minimizes the impact of variables like temperature, plate order and timing on the ratio of experimental/control reporter activity.

Example 1:

An experiment includes 20 plates. If the timing of measurement of the plates is changed between the fi refl y and Renilla luminescence measurements, then the ratio of fi refl y luminescence to Renilla luminescence will be diff erent on each of the plates because the two reporter signals would have decayed by diff erent amounts (changing the order of the plates changes the length of time between reagent addition and plate reading). For instance, the luminometer jammed 20 minutes after the Dual-Glo® Stop & Glo® Reagent was added to a large stack of plates:

Ratio of plate 1 control fi refl y luminescence/Renilla luminescence = 1.7.Ratio of plate 1 well A1 fi refl y luminescence/Renilla luminescence = 3.4.

Both fi refl y luciferase and Renilla luciferase were measured 10 minutes after the reagents were added.

Relative ratios are: control = 1.7/1.7 = 1 and well A1 = 3.4/1.7 = 2.

However, for plate 12 the fi refl y luciferase was measured 40 minutes after Dual-Glo® Luciferase Reagent was added, but because of the luminometer jam, the Renilla luciferase was not measured until 75 minutes after the Dual-Glo® Stop & Glo® Reagent was added.

Ratio of plate 12 control fi refl y luminescence/Renilla luminescence = 2.1.Ratio of plate 12 well A1 fi refl y luminescence/Renilla luminescence = 4.2.Relative ratios are: control = 2.1/2.1 = 1 and well A1 = 4.2/2.1 = 2.


Example 2:

The Dual-Glo® Assay is being performed in a cell culture medium (MEM) that causes the fi refl y and Renilla luciferases to decay at diff erent rates (fi refl y luciferase retains ~90% activity over 2 hours, Renilla luciferase retains ~75% activity over 2 hours). Normalizing the ratios permits comparison of these ratios between plates in the same experiment.

Ratio of plate 1 control fi refl y luminescence/Renilla luminescence = 6.4.Ratio of plate 1 well A1 fi refl y luminescence/Renilla luminescence = 1.6.

Both fi refl y luciferase and Renilla luciferase were measured 10 minutes after the reagents were added.

Relative ratios were: control = 6.4/6.4 = 1 and well A1= 1.6/6.4 = 0.25.

For plate 12, both fi refl y luciferase and Renilla luciferase were measured 65 minutes after the reagents were added, but the two signals do not decay at the same rate. Thus the raw ratio changes.

Ratio of plate 12 control fi refl y luminescence/Renilla luminescence = 6.9.Ratio of plate 12 well A1 fi refl y luminescence/Renilla luminescence = 1.7.Relative ratios are: control = 6.9/6.9 = 1 and well A1 = 1.7/6.9 = 0.25.

Other factors may aff ect the ratio of experimental/control reporter. As seen in Section 6.D and mentioned above, chemical components of the medium/serum combination aff ect the fi refl y luciferase signal stability diff erently than they aff ect the Renilla luciferase signal stability. This is also true of changes in temperature and other parameters that aff ect enzyme reactions. Normalization of the experimental/control reporter activity is essential for easy comparison of samples with minimal variability across an experiment.

Relative Response Ratios

A Relative Response Ratio (RRR) can be determined to assist in quantitation of the impact of an experimental treatment on reporter gene expression. The RRR permits the comparison of multiple treatments from diff erent experiments because it provides a framework within which the eff ect of the treatment can be placed.

Calculation of RRR requires the inclusion of 2 sets of controls on each plate: a positive control that provides maximal luminescence, and a negative control that provides minimal luminescence. For an experiment that monitors down-regulation of the experimental reporter by chemical treatments, the positive control for the experimental series might be no treatment. The negative control would be treatment with some compound that had previously been shown to drastically inhibit the experimental reporter. If these 2 samples are included on every plate, the impact of each new compound can be quantitatively evaluated by its infl uence on the experimental reporter within the context of the positive and negative control.


6.C. Data Analysis (continued)

Example:

If the ratio of experimental reporter luminescence/control reporter luminescence is 53 for the positive control, 1.3 for the negative control, and 22 for the experimental treatment, all of these values can be scaled so that the positive control is assigned the value of 1 and the negative control is assigned the value of 0. The RRR for each experimental treatment can then be calculated using this formula:

RRR = (experimental sample ratio) – (negative control ratio)

(positive control ratio) – (negative control ratio)

The RRR for the experimental treatment example listed above would be:

RRR = 22 – 1.3

= 0.40 or 40% 53 – 1.3

The experimental compound is 40% as eff ective as the negative control at decreasing expression of the experimental reporter at this concentration. A hierarchy of effi cacy for the experimental system would be: i) no treatment generated a RRR of 100%; ii) the experimental compound generated a RRR of 40% and; iii) the negative control generated a RRR of 0%. Those compounds that are most signifi cant will have RRRs that are negative, since they would be more eff ective inhibitors than the negative control.

Note: If the absolute luminescence values are close to background, the luminescences will need to be background subtracted before the ratios are calculated.

6.D. Conditions Aff ecting Assay Performance

The data presented in this section are intended to provide a general overview of assay characteristics under a wide range of experimental conditions. The cell culture medium accounts for 50% of the fi refl y luciferase and 33% of the Renilla luciferase reaction volumes. Thus medium can aff ect assay performance. The chemistry used for the Dual-Glo® Luciferase Assay System is unique when compared to other assays developed for high-throughput analysis and compared to the DLR™ Assay System. Therefore the data presented in this technical manual may not be applicable to other luciferase assay systems.

Purifi ed fi refl y and Renilla luciferases were diluted into culture medium to generate the data presented in this section. This was done to illustrate the performance characteristics without adding the experimental complexities common to cell culture. However, as shown in Figure 6, purifi ed luciferases diluted into culture medium show little or no diff erence when compared to enzymes expressed in transfected cells. Gelatin (1mg/ml) was added to the wells to simulate the protein that would normally be contributed by cells. Addition of gelatin is not required when using the Dual-Glo® Luciferase Assay System with cells.


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Figure 6. Reaction kinetics for purified firefly and Renilla luciferase and for luciferases expressed by transiently transfected mammalian cells. Samples in 96-well plates consisted of 75µl of either purified firefly and Renilla luciferases (both at 1.67 × 10–9M, 1mg/ml gelatin as a protein carrier) or mammalian cells transfected with firefly and Renilla luciferase genes (using pCI Mammalian Expression Vector [Cat.# E1731] with luc+ inserted at XbaI/XhoI sites for firefly luciferase and the phRL-SV40 Vector for Renilla luciferase [Cat.# E6261]) in the same growth medium. Seventy-five microliters of Dual-Glo® Luciferase Reagent was added to plate wells and mixed on a plate shaker. After a 10-minute room temperature incubation, luminescence was integrated over 0.5 seconds per well, periodically, for 2 hours after reagent addition. Stop & Glo® Reagent was then added to wells and mixed on a plate shaker, and luminescence was integrated as noted above. Firefly luciferase was measured in CHO cells in F12 medium (Panel A) and in 293 cells in DMEM (Panel B). Renilla luciferase was measured in CHO cells in F12 medium (Panel C) and in 293 cells in DMEM (Panel D). As these data show, very little difference in relative luminescence is apparent over time between transfected cells and purified enzyme in the same culture medium. Number of samples = 6 for cell lysate data, 3 for purified enzyme data.


6.D. Conditions Aff ecting Assay Performance (continued)

Culture Medium

When performing the Dual-Glo® Luciferase Assay, the culture medium and any compounds added to the medium make up half of the chemical environment of the fi refl y luciferase reaction, and one-third of the environment of the Renilla luciferase reaction. Although the Dual-Glo® Reagents are designed to work with many common culture media, compositional diff erences between the diff erent media may aff ect the assay characteristics (i.e., light intensity and signal stability).

The Dual-Glo® Luciferase Reagents were designed to provide relatively high luminescence, with a half-life of approxi-mately 2 hours when used with common growth medium. However, performance diff erences are evident between these media (Figure 7), as well as between the same media from diff erent manufacturers. Although these diff erences are generally small and do not diminish the utility of the Dual-Glo® Luciferase Assay System, controls should be incorpo-rated into every batch of plates to correct for this variability.

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Figure 7. Relative luminescence intensity and signal stability of fi refl y and Renilla luciferase in four common media. Purifi ed fi refl y or Renilla enzyme (1.67 × 10–9M, 1mg/ml gelatin) was added to a 96-well plate at 100µl per well. Dilutions were made in RPMI 1640, DMEM, MEM or F12 medium. Either Dual-Glo® Luciferase Reagent (for fi refl y luciferase) or Dual-Glo® Luciferase Reagent plus Dual-Glo® Stop & Glo® Reagent (for Renilla luciferase) was added, and luminescence measurements were integrated over 0.5 seconds per well. Panel A. Luminescence measurements were taken 10 minutes after reagent addition. Luminescence is shown relative to the light output generated in RPMI 1640 for both fi refl y and Renilla luciferases. Panel B. Signal stability in various media expressed as percent luminescence remaining after 2 hours. Number of samples = 3; relative standard error 3.4%.


Serum

The Dual-Glo® Reagents are compatible with medium containing serum. The reagents have been designed for use with serum concentrations from 0–10%, and the luminescent signals generated are minimally aff ected by the presence of fetal bovine or calf serum (Figure 8).

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Figure 8. Eff ects of serum on luminescence intensity and signal stability. Purifi ed fi refl y or Renilla luciferase (1.67 × 10–9M, 1mg/ml gelatin) was added to a 96-well plate at 100µl per well. F12 medium containing various concentrations of either fetal bovine serum (FBS) or calf serum (CS) was used for the assay. Either Dual-Glo® Luciferase Reagent (for fi refl y luciferase) or Dual-Glo® Luciferase Reagent plus Dual-Glo® Stop & Glo® Reagent (for Renilla luciferase) was added, and luminescence measurements were integrated over 0.5 seconds per well. Firefl y luciferase relative luminescence (Panel A) and signal stability (Panel B) were measured in medium containing fetal bovine serum (FBS) and calf serum (CS). Renilla luciferase relative luminescence (Panel C) and signal stability (Panel D) were measured in medium containing various concentrations of FBS and CS. Luminescence was compared for samples containing serum and for samples containing no serum. Signal stability expressed as percent of luminescence remaining after 2 hours. Number of samples = 3; relative standard error 3.9%.



Phenol Red

Phenol red is a pH indicator commonly used in cell culture media. Many commercial media formulations contain 5–15mg/L phenol red, causing the characteristic red color. This compound can reduce assay sensitivity (Figure 9). However, in most applications the presence of phenol red will not signifi cantly aff ect the utility of the Dual-Glo® Luciferase Assay System. To minimize its eff ect, use as little phenol red as possible in culture medium.

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Figure 9. The eff ect of phenol red on luminescence intensity and signal stability. Purifi ed fi refl y or Renilla luciferase (1.67 × 10–9M, 1mg/ml gelatin) was added to a 96-well plate at 100µl per well. MEM containing various concentrations of phenol red was used for the assay. Either Dual-Glo® Luciferase Reagent (for fi refl y luciferase) or Dual-Glo® Luciferase Reagent plus Dual-Glo® Stop & Glo® Reagent (for Renilla luciferase) was added, and luminescence measurements were integrated over 0.5 seconds per well. Luminescence is compared for samples containing phenol red and for samples containing no phenol red. Panel A. Luminescence is shown relative to that measured without phenol red. Panel B. Signal stability in various concentrations of phenol red expressed as percent of luminescence remaining after 2 hours. Number of samples = 3; relative standard error 4.0%.


Organic Solvents

Organic solvents are typically present in reporter gene assays, because they are used to stabilize and solubilize screening compounds. DMSO, ethanol and methanol have little eff ect on the assay (Figure 10). The compatibility of other solvents should be verifi ed prior to use.

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Figure 10. The eff ect of organic solvents on luminescence intensity and signal stability. Purifi ed fi refl y or Renilla luciferase (1.67 × 10–9M, 1mg/ml gelatin) was added to a 96-well plate at 100µl per well. F12 medium containing various concentrations of DMSO, methanol or ethanol was used for the assay. Either Dual-Glo® Luciferase Reagent (for fi refl y luciferase) or Dual-Glo® Luciferase Reagent plus Dual-Glo® Stop & Glo® Reagent (for Renilla luciferase) was added, and luminescence measurements were integrated over 0.5 seconds per well. Firefl y luciferase relative luminescence (Panel A) and signal stability (Panel B), as well as Renilla luciferase relative luminescence (Panel C) and signal stability (Panel D) were determined in various concentrations of solvent. Luminescence is expressed relative to samples without organic solvents. Signal stability is expressed as percent of luminescence remaining after 2 hours. Number of samples = 3; relative standard error 4.0%.



Temperature

Both fi refl y and Renilla luciferases are temperature sensitive, thus temperature is an important factor in experimental precision (Figure 11). Good precision can be achieved most easily by performing all experiments at room temperature, which is near the temperature optima for both fi refl y and Renilla luciferases. The assay reagents should be at room temperature before beginning measurements.

As mentioned previously, the Dual-Glo® Buff ers can be stored at room temperature to avoid the need for temperature equilibration before use. The heat capacity of the substrates is low; therefore reconstitution of the Dual-Glo® Substrates with the room temperature Dual-Glo® Buff ers produces reagents that are ready for use. If temperature equilibration is needed, incubate reagents in a water bath at room temperature. Do not use a water bath set higher than 25°C.

Lower temperatures result in increased signal stabilities but lower luminescent intensities. If cold reagent is used, the luminescence will slowly increase during the experiment as the reagent warms. High temperatures aff ect fi refl y and Renilla luciferases diff erently; however, both signals become less stable. This can occur if the culture plates are too warm or if the luminometer produces excess heat within the reading chamber. As shown in Figure 11, fi refl y luciferase is more sensitive to changes in temperature than Renilla luciferase.

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Figure 11. The eff ect of temperature on luciferase luminescence. Purifi ed fi refl y or Renilla luciferase (1.67 × 10–9M, 1mg/ml gelatin) was added to a luminometer tube containing 100µl of Dual-Glo® Luciferase Reagent (for fi refl y luciferase) or Dual-Glo® Luciferase Reagent plus Dual-Glo® Stop & Glo® Reagent (for Renilla luciferase). Samples were incubated at various temperatures, and light emission was measured on a Turner Designs Model 20e luminometer, integrated over 10 seconds after a 2-second preread delay. Panel A. Luminescence at 10 minutes is shown relative to that measured at 22°C. Panel B. Signal stability at various temperatures is expressed as percent of luminescence remaining after 2 hours. Number of samples = 3; relative standard error 3.1%.


(a)U.S. Pat. Nos. 7,078,181, 7,108,996 and 7,118,878, European Pat. No. 1297337 and other patents pending.

(b) U.S. Pat. No. 5,744,320, European Pat. No. 0 833 939 and Japanese Pat. No. 360160.

(c)Certain applicati ons of this product may require licenses from others.

© 2002, 2005, 2006, 2009, 2010, 2011, 2015 Promega Corporati on. All Rights Reserved.

Dual-Glo, Dual-Luciferase, GloMax, Quanti Lum, Steady-Glo and Stop & Glo are registered trademarks of Promega Corporati on. Bright-Glo, DLR, EnduRen, PureYield and ViviRen are trademarks of Promega Corporati on.

FuGENE is a registered trademark of Fugent, LLC., USA.

Products may be covered by pending or issued patents or may have certain limitati ons. Please visit our Web site for more informati on.

All prices and specifi cati ons are subject to change without prior noti ce.

Product claims are subject to change. Please contact Promega Technical Services or access the Promega online catalog for the most up-to-date informati on on Promega products.

6.E. Summary of Changes

The following change was made to the 9/15 version of this document:

Expired patent information was removed.

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